Electron discharge device



April 21, 1936. 5 BRUCHE 23038341 ELECTRON DISCHARGE DEVICE Filed May25, 1955 INVENTOR ERNST BRUCHE Patented Apr. 21, 1936 UNITED STATESPATENT OFFICE ELECTRON DISCHARGE DEVICE many Application May 23, 1935,Serial No. 22,955 In Germany June 7, 1934 3 Claims. (Cl. 25027.5)

My invention relates to electron discharge devices of the gas type, moreparticularly to improvements in oxide coated cathodes therefor.

The conventional type of oxide-cathode mount- 6 ed in gas dischargetubes may have the oxide coating destroyed as a result of the impact ofpositive ions. Two methods have been employed to prevent this result.One is to apply the oxide material upon a wire in the axis of the pathof 10 the electron stream or beam, while according to the other methodthe cathode surface bearing the oxide is positioned annularly about thebeam of reversely flowing ions. In the second case, in more detail, aflat band or strip is dis- 15 posed around the axis of the electron beamor rays, or a small pot or cup may be positioned in the path of the raysso that the lateral surfaces or walls thereof will no longer be struckby the mm.

20 The principal object of my invention is to provide an improved typeof oxide coated cathode for gaseous discharge devices.

According to the present invention the oxide coating on the cathode ismore efiectively shield- 25 ed from the impacts of positive ions than inconventional type tubes. The oxide substance is placed upon the face ofthe cathode sheet or strip turned away from the anode. The lines offorce passing from the anode to the cathode sheet at- 30 tract theelectrons in the path of the ray or beam and guide the same to theanode. According to the invention, apart from excellent protection ofthe oxide, it is possible to use various types of planar cathodes knownin the art which 35 may have the form of sheets or laminae either heateddirectly or indirectly.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims, but the in- 40vention itself will best be understood by reference to the followingdescription taken in connection with the accompanying drawing in whichFigure l is a schematic vertical section of an electron discharge deviceembodying my inven- 45 tion; Figure 2 is a perspective of the electrondischarge device shown in Figure 1; and Figure 3 is a schematic verticalsection of a modification of the electron discharge device shown inFigure 1 and embodying my invention.

50 Referring to Figure 1 the electron discharge device has an envelope econtaining an anode or plate a provided with aperture (1' and thecontrol sheet 8, the anode and control sheet being on opposite sides ofcathode is. On the face of the 55 cathode It turned away from the anodeis a cylinder or sleeve secured concentrically about the aperture 70' inthe cathode sheet, the inner surface of said cylinder being coated withoxide at p. The radius of the cylinder is larger than that of the holeand is surrounded by heater h. 5 The lines of force act, as shown, thruthe cathode sheet and draw the electrons out. The cathode could also beprovided with several holes around which oxide material is disposed. Ofcourse, opposite each of such holes must be a corresponding one in theanode.

In the modification in Figure 3 the oxide p of the cathode is is hereapplied or coated directly upon the posterior face of the cathode sheetis. The small metal block s serves as a control sheet. A heater h isprovided.

While I have indicated the preferred embodiments of my invention ofwhich I am now aware and have also indicated only one specificapplication for which my invention may be employed, it will be apparentthat my invention is by no means limited to the exact forms illustratedor the use indicated, but that many variations may be made in theparticular structure used and the purpose for which it is employedwithout departing from the scope of my invention as set forth in theappended claims. I

What I claim as new is:-

1. A gas discharge device having an envelope containing an anode and acathode, said cathode being formed of sheet material and provided withan aperture, said anode being positioned on one side of said cathode anda cylinder mounted on the other side of said cathode at right angles tothe cathode sheet and around said aperture, and an oxide coating on theinner surface of said cylinder.

2. A gas discharge device having an envelope containing a fiat cathodeprovided with an aperture, a flat anode positioned on one side of andparallel to said cathode, an oxide coating provided on the opposite sideof said cathode from said anode, means for heating said cathode and acontrol electrode positioned on the coated side of said cathode.

3. A gas discharge device having an envelope containing a flat disc-likecathode provided with a single aperture, a flat disc-like anodepositioned on one side of and parallel to said cathode, an oxide coatingdisposed on said cathode on the opposite side of said anode, means forheating said cathode, and a control electrode positioned on the sameside of said cathode as said oxide coating.

ERNST BRUCHE.

